The sex life of the Monarch butterfly is positively wild

Wendy Williams is an enthusiast, and enthusiasm is infectious. Lepidoptery is for her a new fascination, and it shows. On the plus side, her excitement shimmers as freshly as a newly-hatched Adonis Blue. She marvels, and makes us marvel, at the miracles she discovers.

She wonders at the strangeness of a butterfly’s proboscis, which is not, as it appears, a drinking straw (even butterflies cannot suck through a straw longer than their own bodies), but works by capillary action, blotting up fluids and sending saliva down to dissolve sticky or solid secretions. Moths show more variety in their diet, as adults as well as caterpillars — but then there are more than 160,000 known species of moth, and fewer than 20,000 butterflies: there are vampire ones in Siberia and a moth in Madagascar which uses its barbed proboscis to harpoon the eyelids of sleeping birds and drink their tears.

Williams concentrates on butterflies, and chiefly on one species, the Monarch. This is famous for its autumnal mass migrations, flying from as far north as Canada to Florida or California, or down the eastern side of the continent to Mexico. Over-wintering, tens of thousands cluster for warmth on a single conifer and their weight can break branches. In the spring, they become reproductive again, and new butterflies will work their way back up north in successive generations within a single season. Only a specially long-lived ‘super-generation’ will travel up to 3,000 miles south again in the autumn.

That, as Williams would say, is ‘wild’ or ‘cool’. Following the Monarchs, she is amazed by how tough and intelligent they are; how mysterious their navigational skills; how strange their opalescent colours, some created not by pigments but by the reflecting and refracting structures of the scales on their wings; and how alien their compound eyes (they have many more eye-cones than we do and see colours beyond our range.